Amnesia: Its Detection by Psychophysiological Measures

Amnesia: Its Detection by Psychophysiological Measures BRIAN E. LYNCH, M.A.* and JOHN McD. W. BRADFORD, M.B., Ch.B. (VCT), D.P.M. (VCT), F.F. PSYCH. (SA), M.R.C. P S Y C H. ( V . K . ) ** Introduction The term amnesia encompasses many varied examples and causes of memory loss. In an edited text on amnesia, Whitty and Zangwill explore the subject in terms of cerebral disease, trauma, electroconvulsive therapy and psychogenesis. 1 It becomes obvious from the various causative factors involved in amnesia that such a multi-factorial problem requires an eclectic approach in answering. At present, one area being investigated in some detail is alcohoVdrug-induced memory loss. The focus of the present study is the exploration of memory dysfunction resulting from alcohoVdrug abuse. In any discussion of alcohoVdrug-induced amnesia certain features of the dysfunction become important for consideration. Before the amnesia can be examined it must be determined to be either a legitimate loss or a feigned amnesia state. The basis of feigned versus genuine amnesia rests with an individual's biological and psychological resources. Expediency suggests that genuine amnesia tends toward an organic base and feigned toward a psychogenic base. That is to say, the probability of a genuine amnesia is greatly increased when found in concert with organicity. Likewise, feigned memory loss is more likely to be found in individuals suffering from a psychogenic disorder. In addition to the issue of genuine versus feigned amnesia, the type of memory loss is important in any clinical assessment of the disorder. The present study utilizes a clinical breakdown of amnesia type in accordance with characteristics outlined by Bradford and Smith.2 The amnesia states are discussed in relation to the following category types: (A) hazy amnesia: no absolute amnesia either in circumscribed periods or in one complete period; (B) partial (patchy) amnesia: segments of memory loss with no complete period of amnesia; (C) complete amnesia: total ·Mr. Lynch is Course Coordinator, Polygraph Training Section, Canadian Police College, Ottawa. ··Mr. Bradford is Psychiatrist-in-Charge, Forensic Service, Royal Ottawa Hospital and Assistant Professor of Psychiatry, Department of Psychiatry, Faculty of Health Sciences, University of Ottawa. 288 memory loss for one circumscribed period. The clinical evaluation of amnesia is for the most part a very subjective undertaking. Lynch has suggested that conventional clinical assessment techniques are limited in determining the above mentioned amnesia characteristics.3 In essence, the problem stems from the relative unreliability of subjective assessment of memory dysfunction as compared to the objective evaluation of the state by polygraphic measures. Furthermore, both Bradford and Smith, and Lynch have suggested that polygraphic measures when utilized with a standardized detection of deception technique can effectively assist in psychiatric assessments.4,5 Additionally, they describe polygraph's important role in determining the legitimacy of the amnesia and the type and extent of memory loss if found to be genuine.6,7 The use of psychophysiological measures (polygraphy) to detect amnesia is a relatively new psychiatric technique. Although the science of polygraphy is a burgeoning field, only recently has it found its way into the field of psychiatry and in particular forensic psychiatry.s Although polygraphic detection of amnesia appears to be a more objective approach than clinical assessment, Gudjonsson points out that detecting information in amnesia patients by such measures is still dependent on a complex of potentially confounding factors such as recognition, malingering and target stimuli relevance.9 To date, there has not beefl a study that systematically investigated the potential of psychophysiological measures with amnesia states and particularly those induced by alcohoVdrugs. The literature on polygraphy and memory loss is both sparse and diverse in its purpose and methodology. The majority of the amnesia and polygraphy literature suggests there are no particular problems inherent in testing for memory.10,11,12,13 However, Weinstein et (Ii suggest that hypnotically induced amnesia can be very effective in misleading the polygraphic determination.14 This finding was of particular interest to the present study as it might prove to be a confounding variable. Although it can be argued that hypnotic amnesia and alcohoVdrug-induced amnesia have little in common, it must still be considered a potential error source when examining the results. Additionally, Wiggins suggests that visceral or autonomic responsivity is not a sufficiently sensitive measurement modality to detect information in an amnesia state.15 Both these concerns highlighted the necessity of studying memory loss measurement by polygraphic means. In an interesting discussion paper on possible implications of drug induced memory loss for lie detection, Barland suggests that state dependent learning may be an essential factor in utilizing polygraphy With amnesia. Paradoxically however, he concludes the paper by stating that state dependent learning may be purely an academic concern since his practical experience with polygraphy and memory dysfunction did not support any necessity for concern. 16 Amnesia 289 In view of the differences apparent in the literature, the present study was designed to investigate the role that polygraphic measures can play in the detection of alcohol/drug-induced memory loss. Method The study consisted of a series of detection of deception examinations on 22 patients, 20 males and 2 females, all of whom were charged with varied offences and referred for psychiatric evaluation at the Royal Ottawa Hospital, Department of Forensic Psychiatry. Additionally, all patients claimed some degree of alcohol/drug-induced amnesia for the offences charged. The patients ranged in age from 18 to 58 years, with a mean age of 32 years. Unless pertinent to the study, there will be no further breakdown of subjects by sex, such that "patients" will refer to both males and females combined. In addition to the polygraph examination all patients were administered a clinical assessment battery consisting of a psychiatric evaluation, a psychological assessment, a social work assessment and in some cases a neurological assessment. The specific purpose of the polygraph examination was to delineate the type and extent of the purported amnesia - in brief, to assess whether the memory loss was genuine, and if so, for what circumscribed period. All examinations followed the Backster Zone Comparison Technique (control question technique).17 This technique employed a three stage examination procedure. The first stage, employed the pretest interview wherein all information relevant to the offence was gathered from the patient and combined with the information already available prior to testing such as psycho-medical data, family history, police brief etc. As much information as possible was gathered, in order that a clear, concise picture of the critical issue or issues could be identified. This clarity of issue facilitated the formation and ultimate review of the test questions during the pretest stage. The second stage of the examination consisted of administering the reviewed test questions while the patient was monitored psycho physiologically. The instrument used to monitor the autonomic functioning was a four-channel polygraph consisting of two channels measuring respiration and electrodermal activity (skin conductance) and two channels measuring cardiac functioning (relative blood pressure and peripheral blood flow). During this stage the question sequence was administered twice to allow for partial adaptation and habituation. The third stage or post-test interview was primarily designed for the individual who was evaluated as "deceptive." Regardless of determination, all patients were informed of the results and the deceptive patients were given an opportunity to clarify and explain if possible the deceptive response patterns during this stage. Polygraphic interpretation was accomplished by numerically evaluating the polygrams in accordance with the rating rules outlined in the Backster Zone Comparison 290 Bulletin of the AAPL Vol. VIII, No.3 Technique. IS The only modification of the conventional control question technique was in the question formulation. One must always be cognizant of the fact that amnesia is rarely a discrete, concise state of mind. Therefore, in an effort to circumvent some of the problems inherent in the testing of memory loss, the critical questions were worded as follows: "Do you remember distinctly ... " rather than the traditional format of "Did you ...". This modification was suggested by Barland to allow the subject an opportunity to differentiate between what he genuinely remembers of the offence and what he was told about the offence.19 Results The polygraph examination decisions, patients' charges, alcohoVdrug histories, psychiatric diagnoses, and types of amnesia are all outlined in Table 1. To facilitate discussion and analysis certain liberties were taken in grouping the data. That is, had the numbers been of a greater magnitude it would not have been necessary to mass the data as was done here. Twenty-three percent of the patients were charged with theft (armed and unarmed), 18% were charged with rape/indecent assault, 13% with murder/manslaughter, 13% with assault causing bodily harm, 13% with arson, 10% with dangerous use of a

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